Heretofore, various herbicides have been used for the purpose of protecting crop plants, and it has been common to incorporate an adjuvant capable of enhancing their herbicidal effects for the purpose of e.g. reducing the dosage of the herbicidally active ingredient.
GB Patent Publication No. 2309904 discloses a mixture comprising a dicarboxylic acid type compound and an ethoxylated and/or propoxylated triglyceride, and it is disclosed that the herbicidal effect can be enhanced if this mixture is combined with a herbicide. Further, EP 0598515A discloses that the herbicidal effect of a certain specific sulfonylurea compound can be improved by employing an ethoxylated fatty amine type surfactant, and a vegetable oil and/or a mineral oil. However, these references disclose nothing about use of an alkoxylated glyceride to enhance the herbicidal effect of a herbicidal sulfonylurea compound or its salt.
A sulfonylurea herbicide which is commonly and commercially available is one of herbicides having small application dosages. However, from the viewpoint of the environmental problem or economical efficiency, it is desired to further reduce its application dosage. On the other hand, it is possible to reduce the application dosage of a sulfonylurea herbicide by incorporating an adjuvant. However, if the application amount of the adjuvant itself increases, it may adversely affect the environment or the economical efficiency. Thus, it is desired to reduce the application dosages of both the sulfonylurea herbicide and the adjuvant.
Under these circumstances, the present inventors have conducted various studies with an aim to remarkably enhance the herbicidal effect of a sulfonylurea herbicide thereby to reduce its application dosage, and as a result, have accomplished the present invention.